The New York Times is reporting that more than 2,800 dead pigs have been found floating into Shanghai in the Huangpu River, which flows through the city. The incident has raised concerns about contamination of Shanghai tap water.

The carcasses were evidently coming from somewhere upstream, and Chinese officials are currently trying to identify the source of the pigs. The Times report states that the pigs have already been traced to a province south and upstream of Shanghai.

Shanghai officials have stated that Shanghai Waterworks has been checking water quality on an hourly basis. After the first of the pigs had been noticed, Shanghai Waterworks stated that the city’s tap water still met its quality standards.

The report relays that Chinese officials are having samples of the pigs tested to determine their cause of death, which will be known within three days.

The Chinese State-run Global Times reported today that no viruses transmittable to humans have been found on the carcasses yet. Also, the ear tags found on the pigs were found to be scratched up, presumably by someone who knows it is illegal in China to dump dead pigs in a river. The report states that Shanghai authorities are now pressuring authorities from the southern province of Zhejiang to crack down on farmers who may dump dead pigs into the Huangpu rather than dispose of them properly.